What chemical causes shellfish allergy

A kid having an anaphylactic reaction will exhibit typical symptoms of anaphylaxis, such as hives and swelling of the eyes or face, blue skin from lack of oxygen, or pale skin from shock. The airway may be blocked, and the kid may be wheezing as well as confused and feeble. The pulse will be rapid and the blood pressure may be low. Anaphylaxis is an emergency condition that requires immediate professional medical attention.

Once a kid has had an anaphylactic reaction, an allergist should be consulted to identify the specific allergen that caused the reaction.

The allergist will take a detailed medical history and use blood or skin tests to identify the allergen. The allergist will enquire about activities that the kid participated in before the event, food and medications the kid may own ingested, and whether the kid had contact with any rubber products.

Causes and symptoms

The symptoms of anaphylaxis may happen within seconds of exposure, or be delayed 15 to 30 minutes and sometimes even an hour or more later, if the allergen is aspirin or other similar drugs. The sooner the symptoms happen after exposure, the more severe the anaphylactic reaction is likely to be.

What chemical causes shellfish allergy

The first symptoms of an anaphylactic reaction are associated with the skin: flushing (warmth and redness), itching (often in the groin or armpits), and hives. These symptoms are often accompanied by anxiety ; a rapid, irregular pulse; and a sense of impending doom. Then the throat and tongue swell, the voice becomes hoarse, and swallowing and breathing become labored. Symptoms of rhinitis or asthma may also happen, causing a runny nose, sneezing, wheezing, and abnormal high-pitched breathing sounds, further worsening the breathing problems. Gastrointestinal effects may also develop, including vomiting, diarrhea, and stomach cramps.

The kid may be confused and own slurred lecture. In about 25 percent of the cases, the chemicals flooding the blood stream will cause a generalized opening of capillaries (tiny blood vessels), resulting in a drop in blood pressure, lightheadedness, and even a loss of consciousness, which are typical symptoms of anaphylactic shock. The kid may exhibit blueness of the skin (cyanosis), lips, or nail beds.

After the original symptoms happen, there are three possible outcomes:

  1. After initial improvement, the symptoms may reoccur after four to 12 hours (a tardy phase recurrent reaction) and require additional treatment and monitoring.

    Tardy phase reactions happen in about 10 percent of cases.

  2. The symptoms may be mild and fade spontaneously or be quickly ended by istering emergency medication. The anaphylactic episode is over for that specific exposure.
  3. The reaction may be persistent and severe, requiring extensive medical treatment and hospitalization . This condition occurs in about 20 percent of cases.

    What chemical causes shellfish allergy

When to call the doctor

The kid should be given immediate emergency care, if possible, and then taken to the emergency room or the local emergency number (e.g., 911) should be called if symptoms of anaphylaxis develop.


Anaphylaxis is a severe, whole-body allergic reaction.

What chemical causes shellfish allergy

After initial exposure to a substance such as wasp sting toxin, the allergic child's immune system becomes sensitized to that allergen. On a subsequent exposure to the specific allergen, an allergic reaction, which can involve a number of diverse areas of the body, occurs. Anaphylaxis is thought to result from antigen-antibody interactions on the surface of mast cells, connective tissue cells that are believed to contain a number of regulatory, or mediator, chemicals. Specifically, an immunoglobulin antibody protein, IgE, is produced in response to the presence of the allergen.

What chemical causes shellfish allergy

IgE binds to the mast cells, causing them to suddenly release a number of chemicals, including histamine, heparin, serotonin, and bradykinin. Once released, these chemicals produce the bodily reactions that characterize anaphylaxis: constriction of the airways, causing wheezing and difficulty in breathing; and gastrointestinal symptoms, such as abdominal pain , cramps, vomiting , and diarrhea .

Shock can happen when the released histamine causes the blood vessels to dilate, which lowers blood pressure; histamine also causes fluids to leak from the bloodstream

EpiPen Jr., a syringe containing a child's dosage of adrenaline, is used for the emergency treatment of anaphylactic shock.

(© Mark Thomas/Photo Researchers, Inc.)

into the tissues, lowering the blood volume.

What chemical causes shellfish allergy

Pulmonary edema can result from fluids leaking into the alveoli (air sacs) of the lung.

Substances that can trigger an anaphylactic reaction include:

  1. vaccines, including allergy shots and egg- and gelatin-based vaccines
  2. medications, including penicillin, cephalosporin, anesthetics, streptokinase, and others
  3. hormones, including insulin and possibly progesterone
  4. insect stings from hornets, wasps, yellow jackets, honey bees, or fire ants
  5. foods (ingesting even tiny amounts or simply being near the offending food), including peanuts, tree nuts (such as walnuts or almonds), fish, shellfish, eggs, milk, soy, and wheat
  6. rubber latex products
  7. animal and human proteins, including seminal fluid and horse serum (which is used as snake anti-venom)

Anaphylactoid (meaning "anaphylactic-like") reactions are similar to those of true anaphylaxis but do not require an IgE immune reaction.

These are generally caused by direct stimulation of the mast cells. The same chemicals as with anaphylaxis are released, with the same effects, so the symptoms are treated the same way. However, an anaphylactoid reaction can happen on initial exposure to an allergen as well as on subsequent exposures, since no sensitization is required.

There is also a rare helpful of food allergy, called exercise-induced allergy, that is caused by eating a specific food and then exercising. It can produce itching , lightheadedness, hives , and anaphylaxis. The offending food does not cause a reaction without exercise , and, alternately, exercise does not cause a reaction without ingesting the food beforehand.


Anaphylaxis is a severe disorder that has a poor prognosis without immediate treatment. Symptoms are generally resolved with appropriate therapy; therefore, immediate emergency care is essential.


Because of the severity of these reactions, treatment must start immediately.

What chemical causes shellfish allergy

The most common emergency treatment involves injection of epinephrine (adrenaline) to stop the release of histamines and relax the muscles of the respiratory tract. The injection is given in the outer thigh and can be istered through light fabric such as trousers, skirts, or stockings. Heavier clothing may own to be removed prior to the injection. After the injection, emergency services or 911 should be called immediately. A kid with known severe allergic reactions should be carrying an allergy kit with epinephrine; if not, treatment will own to be delayed until emergency personnel can provide the required medication. For reactions to insect stings or allergy shots, a tourniquet should be placed between the puncture site and the heart; the tourniquet should be released every 10 minutes.

If the kid is conscious, he or she should lie below and elevate the feet. If trained, the parents or others present should ister CPR if the kid stops breathing or does not own a pulse. After 10 to 15 minutes, if symptoms are still significant, another dose of epinephrine can be injected. Even after the reaction subsides, the kid should still be taken to the emergency room immediately and monitored for three to four hours, since symptoms can redevelop. Other treatments may be given by medical personnel, including oxygen, intravenous fluids, breathing medications, and possibly more epinephrine.

The epinephrine may make the kid feel shaky and own a rapid, pounding pulse, but these are normal side effects and are only dangerous to those with heart problems. Steroids and antihistamines may also be given but are generally not as helpful initially as epinephrine. However, they may be useful in preventing a recurrent delayed reaction.

If the kid is being treated with beta blocker medications commonly used to treat high blood pressure, angina, thyroid disorders, migraines, or glaucoma, it may be hard to reverse an anaphylactic reaction.

Once a shellfish allergy is identified, the best management is to avoid the food.

You need to carefully check ingredient labels of food products. You should study other names for the foods you need to avoid to be certain not to eat them.

You must be extra-careful when you eat out. Waiters (and sometimes the kitchen staff) may not always know every dish’s ingredient list. Vapors may carry little particles of shellfish protein, so being shut to where food is being prepared can potentially cause a dangerous reaction in sensitive individuals.

Fortunately, shellfish is an ingredient that is rarely “hidden” in foods. Shellfish may be found in fish stock, seafood flavoring (for example, crab extract), sushi and surimi. Crustacean shellfish is one of the eight allergens that drop under the labeling requirements of the Food Allergen Labeling and Consumer Protection Act of 2004.

This means that manufacturers of packaged food items sold in the United States and containing crustacean shellfish or a crustacean shellfish-based ingredient must state, in clear language, the presence of crustacean shellfish in the product. (Note: Those regulations apply only to crustacean shellfish, such as shrimp, lobster and crab, and not to mollusks, such as oysters, scallops and clams.)

Anyone with a food allergy must understand how to read ingredient labels and practice avoidance measures.

Your allergist can direct you to helpful resources, such as special cookbooks, patient support groups and registered dietitians, who can assist you plan your meals.

Many people with food allergies wonder if their condition is permanent. There is no clear-cut answer. Over time, allergies to milk, eggs and soy may vanish. Allergies to peanuts, tree nuts, fish and shellfish typically final a lifetime. About one-third of children and adults with a food allergy eventually outgrow the allergy. But rates of naturally outgrowing food allergies will vary depending on the specific food allergen and the person.

Managing a severe food reaction with epinephrine

Shellfish is among the most common food allergens.

But every food allergies can be dangerous.

Epinephrine is the first-line treatment for anaphylaxis, a severe whole-body allergic reaction that causes symptoms, including tightening of the airway. Anaphylaxis can happen within seconds or minutes of exposure to the allergen, can worsen quickly, and can be deadly.

Once a food allergy diagnosis is made, your allergist likely will prescribe an epinephrine auto-injector and teach you how to use it. Check the expiration date of your auto-injector, note the expiration date on your calendar and enquire your pharmacy about reminder services for prescription renewals.

Be certain to own two doses available, as the severe reaction may recur.

Epinephrine should be used immediately if you experience severe symptoms such as shortness of breath, repetitive coughing, feeble pulse, generalized hives, tightness in the throat, trouble breathing or swallowing, or a combination of symptoms from diverse body areas such as hives, rashes or swelling on the skin coupled with vomiting, diarrhea or abdominal pain. Repeated doses of epinephrine may be necessary.

If you are uncertain whether a reaction requires epinephrine, use it correct away, because the benefits of epinephrine far outweigh the risk that a dose may not own been necessary.

Common side effects of epinephrine may include temporary anxiety, restlessness, dizziness and shakiness.

Rarely, the medication can lead to an abnormal heart rate or rhythm, a heart attack, a sharp increase in blood pressure and fluid buildup in the lungs, but these adverse effects are generally caused by errors in dosing which is unlikely to happen with use of epinephrine autoinjectors.

What chemical causes shellfish allergy

Some people with certain pre-existing conditions might be at higher risk for adverse effects and should speak to their allergist about epinephrine use.

Your allergist will provide you with a written emergency treatment plan that outlines which medications should be istered and when (note that between 10 and 20 percent of life-threatening severe allergic reactions own no skin symptoms). Be certain you understand how to properly and promptly use an epinephrine auto-injector.

Once you own used your epinephrine auto-injector, immediately call 911 and tell the dispatcher that you used epinephrine and that more may be needed from the emergency responders.

Other medications, such as antihistamine and corticosteroids, may be prescribed to treat mild symptoms of a food allergy, but it is significant to note that there is no substitute for epinephrine — this is the only medication that can reverse the life-threatening symptoms of anaphylaxis.

Managing shellfish allergies in children

Because shellfish allergy reactions, love other food allergy symptoms, can develop when a kid is not with his or her parents, parents need to make certain that their child’s school, day care or other program has a written emergency action plan with instructions on preventing, recognizing and managing these episodes in class and during activities such as sporting events and field trips.

If your kid has been prescribed an auto-injector, be certain that you and those responsible for supervising your kid understand how to use it.

This sheet was reviewed and updated as of 2/13/2019.


Anaphylaxis is a severe, sudden, and potentially fatal allergic reaction to a foreign substance or antigen that affects multiple systems of the body.


Although likely an underestimate, about 10,000 cases of anaphylaxis happen per year in North America, with about 750 fatalities a year. The exact prevalence of anaphylaxis is unknown, because milder reactions may be attributed to asthma attacks or sudden cases of hives, and more serious or fatal episodes might be reported as heart attacks, as the initial symptoms of hives, asthma, and swollen throat can fade quickly.

What chemical causes shellfish allergy